1. a) Field of the Invention
This invention relates to a continuously focusable microscope system which incorporates an afocal variator system.
2. b) Discussion of the Prior Art
Microscopes have been in use for centuries. In the past, where it has been desired to alter the focus of microscope systems, this has usually been accomplished over a short range by continuously or discretely changing the length of the optical system of the microscope, or in discrete ranges by changing the location or type of objective lens system in the front, or of any lens system which may be present in the rear, or both the front and rear optical lens systems, if any. Altering microscopical system focal length without utilizing the objective lens system, or changing the length of the optical system, or changing the location or type of lens system in either the front or rear optical system is not believed to be known in the prior art. Continuously focusable microscope systems are not known to applicant. "Varios" and "variators" are well known and useful optical systems. Such systems have found use primarily in zoom lens systems and in projectors, for example, to change the size of a projected image on a screen, but not to focus the image. In many instances, such vario and variator devices have been used, in combination with a front optical system or a rear optical system. In some instances they have even been used in combination with both a front optical system and a rear optical system. However, in all instances known to applicant such optical systems which incorporate vario and variator optical systems have been used to alter the size of an image, but not to focus the image, and are used and usually only function at relatively short back focal distances.
Afocal variators of the specific preferred type described in the present application have been known and in commercial use and on sale, by themselves, for at least fifteen years, for example for use in projector lenses to alter the size of a projected image on a screen. However, while afocal variator optical systems of the specific type disclosed herein, have been previously known in the art, such afocal variator optical systems are not known to have been previously used in the art to focus microscope systems.
In the known prior art, Hillman U.S. Pat. No. 2,937,570 discloses a telescope system in which the image forming lenses are moved in order to focus the system. That is, focusing is accomplished by moving objective lens and focusing lens, which are part of the telescope's "formula-specific" objective imaging system. Focusing is not accomplished or taught to be feasible by moving a portion of an afocal variator, nor by moving a portion of any other non-image forming modular optical lens system. Furthermore, this reference discloses a "formula-specific" optical system in which the lenses are all calculated and assembled to work together to form a telescope. It does not include an independent optical lens system module which is nonimage forming. It does not include a central afocal variator module which does not comprise a portion of the image-forming optics. If any of the movable lenses of any of the systems taught by Hillman were removed, the entire system would be affected, very probably to the point that the system would no longer function for its intended purpose.
In Quenderff French Patent 2,572,545 the use of a zoom lens to make enlarged pictures, and also teaches the use of various art known mechanical devices for connecting together optical modules. However, it neither teaches nor suggests the use of a central afocal variator module as a focusing element.
Therefore, while afocal variator optical systems have been previously known in the art, such afocal variator optical systems are not known to have been previously used in the art to focus microscope systems in the manner disclosed, provided and claimed by the present application. More, specifically such afocal variator optical systems have not been used at a relatively long back focus distance, as opposed to their prior art use to alter image size at a fixed focal plane. It will be seen, that while the use of varios and variators, either alone, or in combination with either a front optical system or a rear optical system are known, they are not known to have been used to provide a microscope system. More specifically, the combination in optical series of a microscope objective lens system with a first positive lens system, a first negative lens system, an afocal variator, and a positive rear optical system, all in combination with one another and with such other components as are required to provide a microscope image, allows the user of such a microscope, to continuously alter the active focal relationships of the microscope by continuously varying the afocal variator and the distance of the microscope objective lens system from the object which is undergoing examination, and all without the need to physically change the length dimension of the microscope system, and without the need to change the positions of any of the lenses outside of the afocal variator, and without the need to change the microscope objective lens. This is quite different than the use of a variator system to alter image size at a fixed focal plane, such as a zoom lens.